karaloop P1.0
The karaloop P1.0 uses flexible strain-gauge contact-based sensors to capture voluntary movements of the face.
It consists of a light headset which incorporates up-to six articulated legs (three legs per side) that can conform the contour of any face, and a control box housing the Bluefruit nRF52 Feather board which is automatically recognized as a human-interface device (HID). The karaloop P1.0 transmits wirelessly preprogramed keyboard or mouse HID commands to any PC, iOS or Android device via BLE. The headset and the control box are connected via two cables relaying sensor signals from both sides of the face to the Bluefruit nR52 Feather board.
The articulated headset legs are made of 3D printed modular Lego-like pieces with ball joints allowing the required adjustments of length and direction to fit any face contour. The modular design further facilitates the easy replacement of faulty pieces. At the end of each leg, a probe incorporates a flexible strain-gauge contact-based sensor that, when in contact with the face, flexes and captures voluntary movements. The signals from the probes are relayed to an electronic hub (one per side) which amplifies and conditions the sensor signals before sending them to the control box.
The karaloop P1.0 (TRL 5) requires further development to improve its operational functionality. The sample provided here incorporates three probes and sends three HID keypresses via BLE.
By using the Bluefruit nRF52 Feather board, the karaloop P1.0 is Arduino compatible. But this requires first installing the Adafruit Bluefruit nRF52 BSP (Board Support Package) and test it. Check Adafruit's Arduino Support Setup for details. Once installed, it is possible to flash sketches using the Arduino IDE.
In this sample, the karaloop P1.0 runs on a firmware sketch and a GUI. The firmware sketch reads the signals from three sensors and translate them into three HID keypresses which are sent via BLE to any device. The firmware also sends the sensor signals to a computer which may be running the GUI. The GUI allows to visualize the sensor signals and helps setting up the thresholds that trigger the keypresses in the firmware, but it is not needed for operating the karaloop P1.0 once the thresholds are set. The GUI was developed using Processing.
Both sample firmware and GUI are a available for download here.
In addition to the Bluefruit nRF52 Feather board housed in the control box, the karaloop P1.0 headset incorporates sensor connecting PCBs housed in each probe and up to four PCBs in each hub which amplify and condition the sensor signals.
Electronic and mechanical design source files are available for download here.
The karaloop P1.0 assembly guide is available for download here.
This wiki documentation work is licensed under a Creative Commons Attribution 4.0 International License.
